1. Field of the Invention
The present invention relates to an image processing apparatus and an image pickup apparatus, which restore an (deteriorated) image that has been deteriorated by an aberration of an image pickup system, to an (original) image or pre-deterioration image.
2. Description of the Related Art
One conventionally known technology is to restore an image deteriorated by an aberration of an optical system (referred to as “image restoration processing” hereinafter). One image restoration processing a method for using information of an optical transfer function (“OTF”) or a point spread function (“PSF”) of an optical system which has a Fourier transform relationship with the OTF.
The OTF has a real part and an imaginary part, and is generally stored as two-dimensional data in storage, such as a memory. This two-dimensional data will be referred to as “OTF data” hereinafter. In the general image restoration processing, OTF data is prepared for each RGB, and the OTF data for one image height is a tap number in the x direction×a tap number in the y direction×2 (real part, imaginary part)×3 (chromatic components). The OTF and PSF are different according to capturing conditions, such as an image height of an image captured via the optical system, and a focal length, an F-value, and an object distance of the optical system.
Japanese Patent Laid-Open No. (“JP”) 2005-308490 proposes a method for interpolating an optical characteristic of glasses having an arbitrary object distance, and JP 2003-132351 assumes an elliptical PSF, and a method for generating a PSF through an interpolation according to an image height position.
The above methods of storing OTF data for each chromatic component and for at least one of capturing conditions cause a data amount to be enormous. Accordingly, this inventor attempts to store discrete OTF data corresponding to representative capturing conditions in an image processing apparatus (or image pickup apparatus), and to generate OTF data corresponding to remaining capturing conditions through an interpolation utilizing stored OTF data. At this time, there is a trade-off relationship between a reduced data amount of the OTF data and the interpolation accuracy (image restoring precision).
However, when PSF or OTF data are interpolated while the center-of-gravity positions of the PSFs used for the interpolation are discarded with each other (or primary components of the phases of the OTFs are discarded with each other), the interpolation cannot be highly precise. Prior art is silent about a solution for this problem.